With a command from their human controllers, robots from all four companies -- Northrop Grumman, HDT Robotics, iRobot Corp. and QinetiQ – opened fire and hit pop-up targets on a ridge about 150 meters away. Using sensors, the robots can pinpoint the enemy, but military officers said a human will make the decision of whether the robot fires on them.

In this image, smoke and dust rise after HDT Robotics' robot, the Protector, fires at the targets.

HDT Robotics’ robot, the Protector, is ready to fire its M240 machine gun at the Red Cloud Range at Fort Benning. The robot, which is chained as a safety precaution, was one of four that demonstrated live fire capabilities for the military. Army officials said they wanted to get an idea of what technology is available to them.

The Protector, the robot from HDT Robotics, takes aim and fires its machine gun at a line of pop-up targets. Both the U.S. Army and the U.S. Marines have tested prototypes of weaponized robots on the battlefield. However, armed robots are not currently in the Army's inventory of weapons.

Northrop Grumman’s CaMEL robot can be equipped with a machine gun, a grenade launcher, an automatic weapon and an anti-tank missile launcher. It also can be used to carry hundreds of pounds of supplies and to recharge soldiers’ batteries in the field.

Northrop Grumman’s robot, the CaMEL, can identify targets from three-and-a-half kilometers away, using a daylight telescope or thermal imaging. The robot, which can run for 24 hours on three-and-a-half gallons of fuel, also can be dropped into a war zone from a helicopter or a plane.

Jason Lohse, of Northrop Grumman, uses a computer and a handheld device, both attached to his vest, to fire an M240 machine gun on the company's CaMEL robot. The vest, which weighs about 10 pounds, also carries a battery and a tablet that flips down from the soldier's chest so he can see what the robot sees. That means the soldier doesn't have to be physically near the target.

Northrop Grumman’s Jason Lohse can see what the robot sees via a tablet computer attached to his vest or on a drop-down eye piece attached to his helmet. Lohse operated the company’s robot during the live fire demo.

A battery and connections for the Northrop Grumman vest are attached to the back of it. With the vest, a soldier can control the weaponized robot from a distance, enabling soldiers to stay back and protected while the robot engages the enemy.

QinetiQ was one of the four robotics companies that demonstrated their weaponized robots at the Army’s robotics demo last week. QinetiQ, which equipped its Modular Advanced Armed Robotic System (Maars) with a machine gun, has robots that range from 10 pounds to more than 12,000 pounds working with the military.

QinetiQ demonstrates its weaponized robot for the Army, which is interested in using robots to give soldiers heavy fire power backup. Such support is particularly important when larger guns or tanks aren't available.

The iRobot team takes its robot out to the firing range. The military envisions having robots that work along side soldiers more as teammates than as tools. The idea is for the robots to either be air dropped or travel with the soldiers as they patrol on foot.

Even though robots, like iRobot’s machine, can home in and fire on a target, it’s likely to be years before weaponized robots will become part of the Army’s arsenal, preceding soldiers into dangerous areas.